This invention relates to the formation of a solar heating panel and more particularly to apparatus and method which forms such a solar heating panel quickly and efficiently.
Apparatus is known for forming flat sheets from filament led onto the periphery of a rotating drum, in which adjacent turns of the wound filament thus formed is removed from the surface of the drum and cut in a direction parallel to the cylindrical axis, so that when the walls of the cylinder are thereafter laid flat, a flat sheet formed from the filament is obtained. Such a device is seen in U.S. Pat. No. 2,442,946.
A machine for fabricating a cylinder from a hollow filament is disclosed in U.S. Pat. No. 2,968,334, which has a short rotating drum onto which the hollow filament is wound. The tubing may be supplied by an extruding machine or from a reel containing such tubing. A stop member is located at one edge of the drum which contacts the hollow filament while it is being wound onto the drum. The stop member surface which contacts the filament rises along a helix axially of the drum. This forces the adjacent filament turns together and forces the cylinder which is formed off of the free end of the drum.
When a hollow tubing is wound on the periphery of a drum to form a cylinder having walls consisting of the spiral turns of the hollow tubing, the tubing has a tendency to twist as it is fed onto the periphery of the drum and to arbitrarily shift axially on the periphery of the drum as it is placed thereon. Moreover, a continuous length of hollow tubing provided at a predetermined speed presents difficulties in forming a cylinder on the periphery of the drum from a spiral of the hollow tubing with adjacent turns bonded together. The speed at which the drum is driven may be greater than the predetermined supply speed, which will cause the continuous length of hollow tubing to deform or break. The peripheral speed of the drum may be less than the hollow tubing supply speed, in which case the spiral turns are loose on the periphery of the drum, may actually overlap, and axial position thereon becomes difficult to control.
It is therefore desirable to obtain apparatus and method for forming a cylinder from a continuous length of hollow tubing supplied at a controlled tubing velocity, and disposed in a spiral with adjacent turns of the spiral being forced together with predetermined pressure, so that adjacent turns may be bonded securely together along the entire length of the tubing.